1. Field of the Invention
The present invention relates to a dielectric ceramic composition, a multilayer ceramic capacitor and an electronic device, and particularly relates to a dielectric ceramic composition being excellent in all of permittivity, capacity-temperature characteristics and a high temperature load lifetime even when dielectric particles composing the dielectric ceramic composition are made finer.
2. Description of the Related Art
In recent years, electronic apparatuses have been rapidly made downsized and higher in performance, and there has been a demand for electronic devices to be mounted in the electronic apparatuses to be also downsized and higher in performance. Multilayer ceramic capacitors as an example of the electronic devices have been demanded to be downsized and to have a larger capacity.
Also, these electronic apparatuses are used under various environments depending on the use objects, so that high reliability is demanded in temperature characteristics and lifetime, etc.
As necessary characteristics to satisfy such demands, a stable capacity-temperature change rate and a long durability under severe conditions as well as high permittivity may be mentioned.
Thus, to solve these points, the present inventors have studied on subcomponents of a dielectric ceramic composition and developed a capacitor having well-balanced permittivity, capacity-temperature change rate and high temperature load lifetime as disclosed in the Japanese Unexamined Patent Publication No. 2005-104772.
However, the present inventors pursued furthermore improvement of performance and obtained knowledge that dielectric particles composing the dielectric ceramic composition had to be finer to make the dielectric layers thinner and larger in number. When actually attempting to make the dielectric particles of the dielectric ceramic composition finer as disclosed in the Japanese Unexamined Patent Publication No. 2005-104772, it turned out that the specific permittivity abruptly declined when an average particle diameter of the dielectric particles became 0.35 μm or smaller.
Namely, when making the dielectric particles finer, particularly when the average particle diameter of the dielectric particles is made 0.35 μm or smaller, approaches of the related art to improve the characteristics turned out to be ineffective.